The invention relates to a method for supervising correct belt utilization in a motor vehicle and to an evaluation system for carrying out this method.
It is a legal provision that the occupants of motor vehicles use safety belts during the journey, which is why corresponding supervising systems are installed in modern motor vehicles, which supervising systems detect whether the belt tongue of the associated safety belt has been correctly inserted into the belt lock at a vehicle seat occupied by a person. If the known supervising systems determine that the belt tongue of the associated safety belt is not inserted in the belt lock at a vehicle seat used by a person, a warning signal is given at recurring intervals of time during the journey until the belt tongue of the safety belt has been inserted into the belt lock.
The correct fastening of a safety belt is important in modern motor vehicles not only owing to the restraining function of the safety belt in the event of an accident but also for reasons of safety with regard to operation of airbag systems and driver assistance systems which is as safe as possible. For example, an adaptive cruise control system with a so-called stop-and-go function or with a congestion assistance system can be used with the required safety margin for the driver or else passenger only when these persons have also actually fastened the safety belts.
Since some drivers or occupants of motor vehicles do not have safety awareness for fastening the safety belt, these persons often insert a so-called dummy belt in the form of a sheet metal strip or a truncated belt tongue into the belt lock during daily vehicle use in order to thus feign use of the safety belt. This manipulation of the belt lock or else manipulation of the belt lock electrics decommissions the request to wear a belt in the vehicle. As a result, the conventional safety system of the motor vehicle also incorrectly determines that a belt is being used even though only a dummy belt has been inserted into the belt lock, for example. As a result, the vehicle safety system cannot adapt its safety strategies for operating adaptive driver assistance systems and for airbag control to the situation “belt not fastened”. Systems for detecting the presence of the driver are canceled, which results in incorrect vehicle safety strategies and therefore in increased danger.
In order to detect the seat occupancy of a vehicle seat and, in particular, of the driver's seat in a motor vehicle, seat occupancy sensors or other occupant detection systems can be used, as stated in DE 101 23 472 A1. Such detection systems may also comprise belt sensors which supervise the insertion of the belt tongue into the belt lock, as is known from DE 10 2009 011 609 A1. However, these known systems are not suitable for detecting feigned belt utilization in which a belt tongue is inserted into the belt lock of an occupied vehicle seat without using the safety belt.
US 2009/289443 A1 also discloses a method for supervising belt utilization, which supervises the open and/or closed belt lock state, in which case belt or belt lock sensors are used for this purpose.